HW30S as above. And, also as above, if it was too large initially, a cheaper second hand stock to alter.

Diana 24, especially the 24D with T01 trigger. Not quite sure how good the recent Diana junior rifles are....the Eleven, 240 etc.

Maybe, maybe even something like the Gamo Delta? I once handled one of these which belonged to a club shooter and he said it shot very nicely and was accurate, too. Having recently worked on my Gamo Vipermax I was quite impressed with overall internal finish and build, so if the tiddler was anything like that.......cheap, too.

Cometa 50 seemed quite nice when handled in a shop once, too. Same applies to the SMK, think the "baby" one is the "15"?